 Campbell went on to become one of the pioneers too, publishing papers on fetal biometry, and developing charts of fetal measurements such the biparietal diameter and head circumference, and formulae for estimating fetal weight using ultrasound.He went on to work at Queen Charlotte's Hospital in London, before being appointed Professor of Obstetrics and Gynaecology at King's College Hospital, where he established a fetal medicine unit of international renown (now Harris-Birthright Research Centre for Fetal Medicine), where other leading fetal medicine practitioners such as Kypros Nicolaides, and Charles Rodeck would later train and work.Campbell's work went on to describe the use of ultrasound to diagnose fetal anomalies, and then the use of Doppler ultrasound, in particular uteroplacental Doppler, in the assessment of 'high-risk' pregnancies.